A device for automatic adjustment of the position of the cutting platform relative to the soil for to grain harvesting machines for slopes is known this device maintaining the parallelism between the cutting platform and the ground by means of single action hydrostatic cylinders, connected such that two of them receive the displacements between the front wheel axis and the body because of the body horizontal position and convey these travels through a quantity of liquid to other two cylinders attached between the platform and the body, which in turn, place the platform relative to the body so that the platform lies parallel to the soil.
However, the known device cannot assure precision in operation because of the presence of impurities in the liquid and oil-tube elasticity, so that numerous adjustment and operations resupply of the liquid in the system are necessary.